Polysaccharide isolated from seeds of Plantago asiatica L. induces maturation of dendritic cells through MAPK and NF-κB pathway

Plantago species are used as traditional medicine in Asian and Europe. Polysaccharide isolated from the seeds of Plantago asiatica L. could stimulate maturation transformation of bone-marrow derived dendritic cells (DCs). We found that blocking p38, ERK1/2 and JNK MAPK signal transduction could significantly decreased the PLP-2 induced expression of MHC II, CD86 surface molecules on DCs. Blocking p38 and JNK signal also significantly inhibited the cytokine secretion of TNF-α and IL-12p70 as well, while blocking ERK1/2 signal only decreased the secretion of TNF-α. Meanwhile, DCs in the three MAPK signal-blocking groups showed dramatically attenuated effects on stimulating proliferation of T lymphocytes. Similarly, blocking signal transduction of NF-κB pathway also significantly impaired the phenotypic and functional maturation development of DCs induced by PLP-2. These data suggest that MAPK and NF-κB pathway mediates the PLP-induced maturation on DCs. Especially, among the three MAPK pathways, activation of JNK signal transduction is the most important for DCs development after PLP-2 incubation. And PLP-2 may activate the MAPK and NF-κB pathway by triggering toll-like receptor 4 on DCs.